One evening, a man who happens to be gay is walking home when he notices a bum passed out in an alleyway.  Feeling a bit horny, the gay guy figures the bum is actually somewhat cute, and proceeds to have his way with him.  Afterwards, he leaves $50 on the bum and continues home.

When the bum wakes up the next morning and finds $50, he goes to the liquor store and asks for "$50 of your cheapest alcohol!"  He gets trashed and passes out in the same alley.

That evening, the gay guy walks by again, and repeats the encounter, this time leaving $100.  

When the bum wakes up to find $100, he cann't believe his good luck, and goes to the liquor store to ask for $100 of their cheapest alcohol, gets trashed, and passes out in the alley.

This particular evening, the gay guy is walking home with a gay friend.  When he sees the bum, he tells the friend about what he has been doing, and they BOTH proceed to have their way with the bum, and they both leave $100.

When the bum wakes up the next morning, he immediately takes his $200 to the liquor store and asks for the most EXPENSIVE alcohol $200 will buy.

Shopkeeper:  "What happened to wanting the cheap stuff?"

Bum:  "That cheap stuff makes my ass sore."